1. Field of the Invention
The invention is related to a light guide device that is specially adapted to fulfill the legal regulations of visibility and can be produced in a cost efficient way. More particularly, the invention relates to a light guide device that has openings that allow light to be coupled in at a well defined position.
2. Description of the Related Art
Vehicle lamps, such as side flashing lamps or side marking or riding lamps, frequently use bar-shaped light guides into which the light of a light source, such as in particular an LED, is coupled at the end. Light guides have in particular the advantage that a desired light distribution can be implemented using relatively simple means and very inexpensively.
In U.S. Pat. No. 7,357,549, the structure and function of a typical vehicle lamp with a bar-shaped light guide is describe in detail. FIG. 4 of this patent shows a side flashing lamp 4 which is integrated in an external rear view mirror 1 of a motor vehicle. The side flashing lamp 4 includes bar-shaped light guides 5, which extend substantially horizontally in the installed position on the vehicle. In operation, light is coupled into the light guide 5 at a position dividing the light guide into two parts 5a and 5b, and the light is propagated as far as the oppositely disposed ends and is coupled out there or along the light guide. A part of the light also passes to the exterior (forwardly in the direction of travel) through a light exit opening 3 in the cover cap 2.
This prior art shows a solution with a cut in the light guide and a stepped outer surface of the light guide. By implementing the cut, the material strength is small and the step in the light guide covering the light sourced is as a result quite weak. In addition, the conditions to couple the light into the light guide are not described.
As can be seen therefrom, arranged at the end 10 of the light guides 5, 5′, which is the vehicle end, are light sources in the form of light emitting diodes 11 having its light output coupled into the light guides 5, 5′ in a longitudinal direction L. The major part of the light is passed by total reflection at lateral interfaces to a coupling-out end 7. In that situation, a part of the light is scattered or deflected and, as mentioned, passes to the exterior through the light exit opening 3. The coupling-out end 7 has a bevelled coupling-out surface 8 whose inclination is selected in a way that the light which issues is emitted into a solid angular region which is prescribed by regulation; that is to say substantially transversely with respect to the direction of travel and somewhat inclined rearwardly, as is indicated by arrows F. In that respect, the light emission region is determined by the direction of the light guide at the coupling-out end 7 and the inclination of the bevelled surface 8. The prior art solution does not describe how to couple light into the light guide structure.
US Patent Publication 2004/0257790 discloses a vehicle lamp mounted in a rear view mirror. A bulky light guide member 12 is attached to a mirror and includes a LED that is inserted in a hole in the bulky light guide. The LED is mounted on a printed circuit board. The prior art does not solve the problem of illuminating two parts of a light guide through a recess in a turn signal module.
Document EP1304260 discloses an embodiment in FIG. 72 with an elongated shaped light guide having a recess for two LEDs. The recess of FIG. 72 is not designed as a cut or a structure with well defined surfaces, flat, convex or concave. The LEDs are not inserted to illuminate the two light guide parts similar to separate portions. In this prior art, the two portions of the light guide are not only illuminated by the light sources in the recess, but by an additional light source at one end of the light guide. Therefore, there is no need to couple light into the two portions of the light guide similar to a structure with separated light guides and to optimize recess dimensions.